Observational hints on the torus obscuring gas behaviour through X-rays with NuSTAR data

DOI: 
10.1093/mnras/stab3752
Publication date: 
01/03/2022
Main author: 
Osorio-Clavijo N.
IAA authors: 
Masegosa, J.
Authors: 
Osorio-Clavijo, N.;González-Martín, O.;Sánchez, S. F.;Esparza-Arredondo, D.;Masegosa, J.;Victoria-Ceballos, C.;Hernández-García, L.;Díaz, Y.
Journal: 
Monthly Notices of the Royal Astronomical Society
Publication type: 
Article
Volume: 
510.0
Pages: 
5102-5118
Abstract: 
According to theory, the torus of active galactic nuclei (AGN) is sustained from a wind coming off the accretion disc, and for lo w ef ficient AGN, it has been proposed that such structure disappears. Ho we v er, the e xact conditions for its disappearance remain unclear. This can be studied throughout the reflection component at X-rays, which is associated with distant and neutral material at the inner walls of the torus in obscured AGN. We select a sample of 81 AGNs observed with NuSTAR with a distance limit of D < 200 Mpc and Eddington rate λEdd ≡L bol / L Edd < 10 -3 . We fit the 3-70 keV spectra using a model accounting for a partial-co v ering absorber plus a reflection component from neutral material. We find that the existence of the reflection component spans in a wide range of black hole mass and bolometric luminosities, with only ∼13 per cent of our sample (11 sources) lacking of any reflection signatures. These sources fall in the region in which the torus may be lacking in the L-MBH diagram. For the sources with a detected reflection component, we find that the vast majority of them are highly obscured ( log N H > 23 ), with ∼20 per cent being Compton-thick. We also find an increase in the number of unobscured sources and a tentative increase on the ratio between FeKαemission line and Compton-hump luminosities toward λEdd = 10 -5 , suggesting that the contribution of the FeKαline changes with Eddington ratio.
Database: 
SCOPUS
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2022MNRAS.510.5102O/abstract
ADS Bibcode: 
2022MNRAS.510.5102O
Keywords: 
Galaxies: Active | Galaxies: nuclei | Galaxies: Seyfert | X-rays: Galaxies